The goal of the proposed research is the deveopment of electrophoretic light scattering for the automated electrophoretic analysis of suspensions of living cells and the application of this method to problems of biophysical and medical significance. Preliminary work has shown the technique to be rapid, precise, and reliable for the electrophoretic characterization of various populations of cells including lymphocytes, erythrocytes, and platelets. Projects are proposed to characterize normal and abnormal cells from animals and human subjects to determine the significance of the electrophoretic mobility and the mobility distribution for the detection of subpopulations and for the study of the cell surface and cell surface reactions. For example, the electrophoretic light scattering spectrum may be a way to characterize in a matter of seconds the relative numbers of T cells, B cells, and monocytes in peripheral blood samples. One disease in which preliminary experiments have been quite promising and for which continued experiments are proposed is acute lymphocytic leukemia. The long-term goal of the research is to use this technique to characterize a large number of different cell types with respect to surface charge density and then to make the technique available for the routine electrophoretic analysis of cell suspensions for both research and clinical applications.